Oxidation of hydrocarbyl-metallo compounds



United States Patent 3,324,160 OXIDATEGN OF HYDROCARBYL-METALLOCQMPOUNDS William E. Wright. John C. Benstead, and James D. Shimmin,Cheshire, England, assignors to Shell Gil Company, New York, N.Y., acorporation of Delaware No Drawing. Filed Apr. 12, 1963, Ser. No.272,517 9 Claims. (Cl. 260-448) This invention relates to an improvementin the known methods of oxidizing hydrocarbyl compounds of metals ofGroups IIIB and IVB of the Periodic Table. It deals with a process forcarrying out such oxidations to produce the corresponding hydrocarboxycompounds efficiently and advantageously.

It has been known for some time that aluminum, boron, lead, silicon andtin compounds having one or more bydrocarbon groups (R) such as alkyl,aryl, alkaryl, aralkyl, and cycloalkyl groups linked directly to themetal atom can be oxidized to hydrocarboxy compounds in which one ormore of these hydrocarbon groups is converted to a hydrocarboxy group(OR) directly linked to the metal atom. Thus, for example, aluminum andboron alkoxides can be made from the trialkyl aluminums and trialkylborons, and aluminum and boron phenoxides can be made from triphenylaluminum and triphenyl boron compounds. These oxidation products areparticularly useful as intermediates for the alcohols and phenols intowhich they are converted on hydrolysis. Methods for carrying out theseoxidations and hydrolyses are described in US. Patents 2,863,895,2,873,290, 2,892,858, 3,016,397, and 3,048,612, for instance.

The prior methods for producing alcohols and phenols in this way havebeen found to give undesirably low yields with some of these hydrocarbylcompounds due chiefly to low conversions to the desired hydrocarboxymetal compound in the oxidation step. An important object of the presentinvention is the provision of a process which overcomes thedisadvantages of the prior methods of operation. A more particularobject of the invention is to provide a commercially more attractivemethod for the oxidation of hydrocarbon compounds of aluminum, boron,lead, silicon, and tin to hydrocarboxy compounds of these metals. Stillanother object is the provision of an improved method for producingalcohols and/or phenols via such oxidation. Still other objects andadvantages of the new process will be apparent from the followingdescription of the invention.

In accordance with the invention, hy-drocarboxy compounds of aluminum,boron, lead, silicon and/or tin are produced by oxidizing hydrocarbylcompounds of these metals in the presence of a hydrocarboxy compound ofcadmium or zinc.

The mechanism whereby the cadmium or zinc hydrocarboxy compounds alfectsthe improved oxidation of the hydrocarbyl compound of the Group III-Band/or Group IVB metal is not a feature of the invention nor essentialto an understanding of the new process. However, the improved resultswhich are achieved can be explained on the basis that the oxidationpromoters used in accordance with the invention are cadmium and/or zinccompounds which can form hydrocarbyl compounds having a hydrocarbylgroup which, under the oxidation conditions employed, is more readilyoxidized than the most difiicultly oxidized hydrocarbon radical of theGroup III-B and/or Group IVB metal compounds which is to be converted toa hydrocarbyloxy group. The relative ease of oxidation here referred tois readily determined by measuring the maximum percentage conversion ofhydrocarbon radical to hydrocarboxy radical of the metal compounds beingcompared, using comparable oxida tion conditions. These oxidationpromoters may function via some kind of radical interchange during thecourse of the oxidation. Such interchange is thought to result intransfer of a diflicultly oxidizable hydrocarbon radical of the GroupIII-B or Group IVB metal compound to the cadmium or zinc atom of theoxidation promoter. The hydrocarboxy radical from the promoterpresumably is transferred to the Group III-B or Group IVB metal atom. Onbecoming attached to the cadmium or zinc atom, the previouslydiflicultly oxidizable hydrocarbon radical becomes more easilyoxidizable to a hydrocarboxy radical which is then available for furtherradical interchange with hydrocarbon radicals of the Group III-B or IVBmetal. Typical of the changes which take place in such a series ofreactions when starting with a trior tetrahydrocarbyl metal compound MRare those shown in the following equations:

Here M is the metal of Group III-B or IVB, particularly aluminum, boron,lead, silicon, or tin, whose valence n is 3 or 4. R and R arehydrocarbon radicals. R" is a hydrocarbon R or hydrocarboxy radical--OR, and X is an atom of cadmium or zinc. For the sake of simplicity,only the replacement of two hydrocarbon radicals of the compound MR byhydrocarboxy radicals have been shown in the equations. It will beapparent, however, that through further oxidation of the cadmium or zinccompound R'-XR and exchange of radicals in the same way, all thehydrocarbon radicals on the Group IIIB or IVB metal can be converted tohydrocarboxy radicals. The final oxidation product will then be amixture of hydrocarbyloxy compounds of the starting cadmium or zinc andGroup IIIB and/or Group IVB metals. These on hydrolysis will yieldalcohols and/or phenols R-OH and R'OH which may be the same if thehydrocarbon radicals R and R are identical, or may be mixtures of up to5 or 6 different hydroxy products where the hydrocarbon groups ofcompound MR are not all the same and/ or the hydrocarbon groups R of thecadmium or zinc hydrocarboxy compound R"XOR are different. Complexproducts will of course also be produced when using mixtures ofdifferent starting compounds instead of the single compounds MR andR"XOR indicated in the foregoing equations.

The cadmium or zinc hydrocarboxy compound which must be present in theoxidation mixture according to the invention, can be added as such orcan be formed in the mixture from a suitable added precursor. Because oftheir ready oxidation to the corresponding hydrocarboxy compounds,hydrocarbyl compounds of cadmium and zinc are especially suitable asprecursors for the formation of the oxidation promoters in situ.Applicants have found that other cad-mium and zinc compounds can also beadded to the oxidation reaction mixture to promote the formation ofhigher yields of desired oxidation products of the starting Group IIIBand Group IVB metal compounds. These can be any of the cadmium and zinccompounds which react under the oxidation conditions used with the GroupIII-B and Group IVB metal compound being oxidized or with some othercomponent of the mixture to form a hydrocarbyl or hydrocarboxy compoundof cadmium or zinc. The invention is therefore not limited as to themanner in which the cadmium and/or zinc hydrocarboxy compound whichfunctions as the oxidation promoter is introduced into the oxidationmixture.

The results of applicants investigations in connection with the presentinvention show that other variations can be made in the manner in whichthe oxidation promoter is made available in the oxidation mixture. Forexample, in the oxidation of a Group IIIB and/ or Group IV-B metalhydrocarbyl (MR starting material, the promoter can be added theretobefore oxidation commences or it can be added to the reaction mixtureduring oxidation at any time not later than the stage at which asubstantial conversion of MR to M(OR) R has occurred. One can also ofcourse utilize a compound M(OR) R as the initial starting material,though such procedure may not be as economically advantageous. It is thefinal stages of the oxidation in which complete conversion of thestarting Group III-B and/ or IVB metal compound to hydrocarboxy compoundis effected that are most difficult to carry out, and it is in thesestages of the process that the oxidation promoter is most advantageous.

As previously pointed out, the cadmium or zinc compound added asoxidation promoter can with advantage be a hydrocarbyl (e.g. an alkyl)compound or a hydrocarboxide (e.g. an alkoxide) and since the requiredamount of added promoter can be small relative to the total amount ofGroup IIIB and/or IV-B metal compound starting materials to be oxidized,it matters little whether the cadmium or zinc compound contains -R orOR' radicals of the same kind as are present in the starting Group III-Band/or IV-B metal compound or its oxidation product(s). For example, alower alkyl (or alkoxy) compound of cadmium or zinc, e.g. zinc diethyl,can be added as the oxidation promoter irrespective of the kind ofstarting material to be oxidized; although on a plant scale, thepromoter can with advantage be a cadmium or zinc hydrocarboxy (e.g.alkoxy) compound corresponding to the hydrocarboxy oxidation product tobe produced. As indicated, only a small amount of oxidation promoter isusually necessary, although the amount actually used in any particularcase may depend on the nature of the starting material to be oxidizedand also on the nature of the cadmium or zinc compound added. As a rule,about 1 mole percent to about 12 mol percent of cadmium and/or zinccompound, based on the amount of Group IIIB and/ or Group IV-B metalhydrocarbon compound being oxidized will be sufficient in the reactionmixture although large amounts can be employed if desired, althoughusually Without compensating advantage. For example, when using a zinccompound (e.g. an alkoxide or alkyl) as a promoter in the oxidation ofan aluminum trialkyl containing to carbon atoms in each alkyl radical anamount of promoter (expressed for convenience in terms of zinc metal)within the range 0.1 to 1.0% by weight of the starting material isusually sufficient, although larger amounts, e.g., up to 1.5 to 2.0% byweight thereof may be used if desired.

It is advantageous to use as oxidation promoter a cadmium or zincorgano-compound which is readily soluble in the reaction mixturecomprising the starting material to be oxidized. It will be understoodthat if desired, an inert solvent, e.g., an alkane may also be presentin the reaction mixture. Suitable promoters are cadmium and zinccompounds which contain a hydrocarboxy group (OR' where R ishydrocarbon) which is capable of interchanging under the oxidationconditions with a hydrocarbon group of the Group III-B or IV-B metalcompound being oxidized. Cadmium and zinc compounds having alkoxy and/oraralkoxy or cycloalkoxy or like groups which contain up to carbon atomsin their hydrocarboxy group or groups are especially useful oxidationpromoters. More preferably, such compounds having 2 to 20 carbon atomsper hydrocarboxy group and having only aromatic double bonds as multiplebonds between carbon atoms are used. Particularly advantageous additivesare the lower alkyls and alkoxides of cadmium and zinc, lower heresignifying less than 10 carbon atoms. Specific examples of suitableadditives are zinc di-normal-propyl; zinc ethyl-n-propyl; zinc didecyl;zinc dibenzyl; zinc di(ethyl-/3-cyclohexyl); zinc di-n-propoxide;

zinc n-propyl-ethoxide; zinc ethoxide-n-propoxide; zincdecyl-n-decoxide; and zinc di-lauryloxide; zinc stearate; zincdi-isopropyl salicylate; and the like; and corresponding compounds ofcadmium.

The oxidation can be carried out in any suitable manner. The methods ofthe previously referred to U.S. patents, for example, are suitable.

Molecular oxygen is the preferred oxidizing medium. It can be used inpure or diluted form, for instance, as air. Ozone or ozonated air isanother oxidizing medium. In some cases it may be advantageous to carryout the oxidation initially with air or even more dilute oxygen andincrease the oxygen content of the oxidizing gas at at a later stage ofreaction, using pure oxygen for the final oxidation.

Temperatures of the order of about 20 C. to about 150 C. are generallysatisfactory although about 40 to about C. is usually preferable. It maybe advantageous to use a lower temperature in this range for the initialoxidation and complete the oxidation at a higher temperature alsopreferably in the indicated operating range. Either atmosphere or higheror lower pressure can be used for the oxidation which can be carried outbatch-wise, intermittently or continuously.

It is a feature of the invention that the new method of oxidizinghydrocarbon compounds of metals of Groups IIIB to IVB of the PeriodicTable can be combined with hydrolysis of the resulting oxidation mixtureto produce alcohols and/or phenols of low solubility in water in anespecially advantageous way. This is because the cadmium or zinchydrocarboxy compound present as oxidation promoter in the first stepnot only improves the oxidation but also has a beneficial effect in thesubsequent production of these alcohols and/or phenols. In thehydrolysis step, the metal corresponding to the Group IIIB or Group IV-Bmetal Whose hydrocarbon compound is being oxidized is converted to themetal oxide in a finely divided suspended form. These oxides accumulateat the interface between the aqueous layer of the hydrolysis product andthe organic layer thereof which contains the water-insoluble alcoholsand/or phenols. Separation of the organic layer and recovery of thealcohol and/or phenol product is made difficult by this contamination ofthe interface. For example, the recovery of higher alcohols fromoxidation of C or higher trialkyl aluminums and hydrolysis of theresulting aluminum trialkoxide is interferred with by the by-productalumina which collects at the interface between the two liquid phasespresent after the hydrolysis mixture is allowed to settle. Thehydrolysis product in the case of the present invention can have theadvantage of a clearer interface between the organic and aqueous layerssince there is less tendency for alumina to collect at this interface.This improvement in the interface is an appreciable improvementprocesswise, and it is believed that the improvement may be due to thefact that oxidation in accordance with the present invention may be morespecific from the point of view of giving rise to fewer and/ or lessdeleterious (from the interface aspect) by-products than in the case ofoxidation in the absence of the cadmium or zinc compounds used asoxidation promoter in the oxidation step of the process.

Any of the prior art methods of hydrolyzing metal hydrocarboxy compoundscan be used in the hydrolysis step of the new combination process forproducing alcohols and/or phenols, the mode of hydrolysis not being afeature of the invention. The previously mentioned patents, for example,disclose methods of hydrolysis which are suitable and which are made apart of the present disclosure by reference as is the disclosure incopending application, Ser. No. 113,599, filed Mar. 31, 1961, by Shimminand Wright, now abandoned, and corresponding Canadian Patent 667,017, ofa more advantageous method of hydrolyzing hydrocarboxy compounds ofmetals of Groups II and III such as zinc and aluminum (a) A C C aluminumtrialkyl starting material was obtained by heating aluminum tri-isobutylwith a C C cracked wax olefin at 145 C. for 1 hour under whichconditions isobutyl radicals were displaced by the longer chain radicalsderived from the C C olefins. The resulting aluminum trialkyldisplacement product was then analyzed to determine the C C alkylradical content thereof, and the amount of aluminum C C trialkyl presentwas calculated from the analytical figures.

(b) The aluminum Cpl-C1 trialkyl (in the form of the displacementproduct containing unreacted cracked wax olefin) was then oxidized inaccordance with the present invention using various zinc hydrocarboxycompounds as oxidation promoter additives. In each oxidation thereaction mixture was maintained at 60 to 90 C. during oxidation, whichwas effected by first passing air and then substantially pure oxygenthrough the reaction mixture at the rate of 26 and 20 liters per hourrespectively. Each oxidation product was hydrolyzed by refluxing withwater for one hour, after which time the organic component was readilyremoved as the result of the clear organic-aqueous interface and analcohol-hydrocarbon fraction distilled therefrom. This fraction was thenanalyzed to determine its alcohol content and from this, the percentageconversion of alkyl to alkoxide was calculated.

(c) By way of comparison oxidation of the C -C trialkyl aluminum wascarried out in the absence of oxidation promoter but under otherwiseidentical conditions.

The conditions employed and the results obtained in all those oxidationsare indicated in the following table where the additives were:

AZinc di-iso-octoxide B-Zinc di-phenoxide CZinc di-isopropoxide DAcomplex: 2NaCl/Zn(OEt) EZinc dicetoxide Example II The C -C trialkylaluminum mixture prepared as in Example I was oxidized in the same waybut using as the oxidation promoters zinc dialkoxide formed in situ fromzinc dialkyls added at the start of the oxidation. The oxidationproducts were hydrolyzed and the alcohols produced were determined as inExample I with the following results for zinc diethyl and zincdi-isobutyl as additives identified as F and G respectively.

the manner described in Example I, and the following results wereobtained:

Amount of C alkyl grams 505 Amount of Cd(OEt) d0 5.7 Al:Cd ratio- Molar:5 Air flow time minutes 252 Oxygen flow time do 54 Amount of C1448alkoxy formed grams 286 Conversion of alkyl to alkoxy percen-t 87Example IV In this example n-hexanol was prepared by oxidation of borontri-n-hexyl followed by hydrolysis and in part (a) of this example theboron trihexyl was oxidized in the absence of an oxidation promoter soas to give comparative data, while in part (b) the boron trihexyl wasoxidized in the presence of added zinc di-isobuntyl as an oxidationpromoter in accordance with the present invention.

(a) Air was blown into a reaction mixture comprising a solution of gramsof boron tri-n-hexyl in grams of toluene at 60 C. for 222 minutes at therate of 26 liters per hour, after which oxygen was blown into thereaction mixture at the rate of 33.4 liters per hour for 180 minutes.The resulting reaction mixture was then subjected to hydrolysis byrefluxing with water for 1 hour and the hydrolysis product distilled togive a distillate containing 81 .grams of n-hexanol. The conversion ofboron alkyl to boron alkoxide was calculated to be 54%.

(b) A reaction mixture comprising 114.7 grams of boron tri-n-hexyldissolved in 106.9 grams of toluene to which had been added 2.20 gramsof zinc di-isobutyl was oxidized under similar conditions to thoseemployed in part (a) of this example. Air blowing was for 285 minutes at26 liters per hour and oxygen blowing was for minutes at 33.4 liters perhour, the reaction being maintained at 60 C. Following hydrolysis anddistillation a distillate containing 86 grams of n-hexanol was obtained.The conversion of boron alkyl to boron alkoxide when operating under theconditions of the present invention was calculated to be 72%. Theboron:zinc molar ratio in the reaction mixture was 98:2, the w./w. ratiobeing 88:12.

Example V l Oxidation of tin tetra-n-hexyl with air and oxygen under theconditions used in Example IV but employing zinc di-n-hexyl as theadditive for in situ formation. of zinc di-n-hexoxide as oxidationpromoter, and hydrolysis of the tin n-hexoxide gives n-hexanol in thesame way.

O "-11; alkyl (grams) I 313 163 252 23s 99 142 172 174 176 152 140 126Additive None None A A A B C D E F G G Additive amount rams) 868.2 1 4,20. 4 13 3 5 3.2 3. 9 898317 1. 3 1 .1 2.

:1 :2 1: 88: 2 8 :1 8 :11 :1 {94. 6:5. 4 s9=11 91:9 94:6 94:6 95:5 951594:6 97:3 94:6 Air flow (mins.) 173 267 186 72 125 132 138 168 196 174150 Oxygen flow (mins.) 152 73 98 125 150 213 172 168 126 47 165 16!)Amount of 014-18 alko deformed (gram 245 128 249 230 31 136 166 156 161144 131 120 Conversion of alkyl to alkoxide, perce11t t 73 73 92 90 8290 90 83 85 88 86 89 Other additives used to produce the oxld-ationpromoter 65 Example VI in situ in oxidation tests carried out in thesame way were zinc chloride and colloidal zinc oxide which were found toalso result in increased yields of aluminum (DH-C18 trialkoxides.

Example III The aluminum Cpl-C13 trialkyl displacement product referredto in Example I was also oxidized in accordance with the presentinvention using cadmium ethoxide as the oxidation promoter additive.Oxidation, hydrolysis and working up of the alcohol product was carriedout in As previously indicated, the present invention is in no waylimited to the production of aliphatic monohydric alcohols by oxidationof e.g. aluminum alkyls, followed by 70 hydrolysis of the alkoxideintermediate, and this example nate from the selective solventextraction of heavy catalytically cracked cycle oil, the selectivesolvent (e.g., liquid sulfur dioxide or furfural) extracting aromaticstherefrom. Both cracked wax olefins and cracked rafiinate olefins areolefin mixtures, the olefins of which commonly contain six totwenty-five carbon atoms per molecule and the olefin mixtures commonlycontain a large proportion of straight chain alpha olefins. However,aluminum trialkyl starting materials for use in the present inventioncan be prepared from other olefins or olefin mixtures, e.g., individualC to C olefins or mixtures thereof or olefins Citronellene (AlfiBu):

Yield of citro- Oxidation Promoter ncllol in mole Grams Moles o1 GramsMoles t 9 1 w./\v. of Al Zn percent based on DMO Active D 0 Air rate: 26liters/hour. Oxygen rate: 30 liters/hour.

The improvement obtained by the use of cadmium and zinc hydrocarboxycompounds as oxidation promoters according to the invention contrastsmarkedly with the results obtained in the oxidation of Group III-B andIVB metal hydrocarbon compounds in the presence of other metal compoundswhich do not give a substantial improvement in the oxidation.

While, as previously pointed out, the invention can be appliedsuccessfully in the oxidation of any compound of a metal of Group III-Bor IV-B having a hydrocarbon group directly linked to the metal atom,the best results are obtained with compounds of these metals havinghydrocarbon groups of up to 30 carbon atoms each. Most preferably thestarting material is a compound of this kind having only hydrocarbyl orhydrocarbyl and hy-drocarboxy groups linked to the metal atom.Especially preferred are the compounds having as hydrocarbyl groups,allyl, aryl, alkaryl, aralkyl, and/or cycloalkyl groups of 4 to 30carbon atoms each and containing as the only multiple bonds ethylenicand aromatic double bonds between carbon atoms. The hydrocarbon radicals(R) may contain substituen-t atoms or groups which do not interfere withthe oxidation of such radicals to the corresponding oxy radicals OR, butgenerally it is preferred to use starting compounds containing only,carbon and hydrogen in the hydrocarbon and hydrocarboxy linked to themetal atoms.

Particularly advantageous results have been obtained in the oxidation ofcompounds of the formula MR where M denotes a metal of Group I'II B, andeach R denotes a hydrocarbon radical, which can be the same or differentradicals selected from the group consisting of the unsubstituted alkyl,aryl, alkaryl, aralkyl, and cycloalkyl radicals having 4 to carbon atomsand the corresponding compounds of the formula M(OR),,R where a is 1, 2,or 3 and b is 3-a. The aluminum and boron compounds of this type areespecially preferred because of the good results which have beenobtained with them. For example, particularly suitable aluminum trialkylstarting compounds can be derived from an olefin or olefin mixtureobtained by the thermal or catalytic cracking of hydrocarbon streamssuch as are produced from crude petroleum feedstocks. For example,olefins may be produced by cracking paraffin wax fractions and theolefin mixtures (e.g., C C olefin mixtures) produced in this way arereferred to herein as cracked wax olefins. Other olefins which may beused for the preparation of suitable aluminum trialkyl startingmaterials are the socalled cracked ratfinate olefins obtained bycracking raffiderived from a Fischer-Tropsch synthesis or obtained, forexample, by the dimerization or trimerization of lower olefins such asethylene, propylene or l-butene or by the tetramerization of propylene.The aluminum trialkyls may contain straightor branched-chain alkylradicals or both.

As will be realized, aliphatic monohydric alcohols are obtained fromaluminum trialkyls in accordance with the present invention, but theinvention is not limited to the production of such alcohols but alsoincludes the preparation of aromatic monohydric alcohols and phenols,cycloaliphatic alcohols, for example, citronel-lol and other hydroxycompounds depending on the choice of starting material.

Suitable aluminum trialkyl starting materials can be prepared by manyprocesses. For example, UK. patent specification No. 770,707 describes aprocess for preparing, e.g., aluminum tri-isobutyl, and the latter canbe reacted with other olefins to form aluminum trialkyls containingalkyl radicals of various carbon chain lengths. For example, the processdescribed in UK. patent specification No. 794,359 enables thepreparation of many different aluminum trialkyl starting materials: forexample, cracked wax or cracked rafiinate olefins can be used to preparelong-chain aluminum alkyls from aluminum tri-isobutyl. Other processesfor preparing aluminum trihydrocarbyls are described in U.K. patentspecifications Nos. 763,824 and 763,081.

In some circumstances, it may be convenient to prepare a long-chainaluminum alkyl starting material for the process of the presentinvention from the corresponding long-chain olefin under conditions inwhich the alkyl product is in admixture with unreacted olefin, and it isto be understood that such a mixture can be used as such as the startingmaterial without prior separation of the olefin.

A special feature of the present invention in one of its modificationsis the provision of a particularly advantageous method for producingstarting material for oxidation by the new process. In thismodification, aluminum trialkyls are prepared by reacting an aluminumtri (lower alkyl) with an olefin or mixture of olefins to effectdisplacement of one or more, preferably all three, of the lower alkylgroups of the aluminum tri (lower alkyl) by higher alkyl groups. Thelower alkyl groups here referred to will usually be groups of l to 4carbon atoms but may contain more carbon atoms. The displacement can becarried out by any of the known methods.

Other tri-hydrocarbyl aluminum and boron compounds useful as startingmaterials for the method of oxidation of the invention can be preparedin other known Ways as can suitable tetra-hydrocarbyl lead, silicon, andtin compounds for use in the new process. Examples of the lattercompounds are, for instance, tetra-octyl lead, tetrahexyl silicon,tetra-dodecyl tin, diphenyl-didecyl lead, tetraphenyl silicon,tetra-allyl lead, tetra-cyclohexyl silicon, and the like.

It will thus be seen that the new process is broadly applicable and canbe carried out in various ways without departing from the invention. Itis, as previously indicated, especially useful for the production ofalcohols and/or phenols by hydrolysis of the oxidation products, but theinvention is not limited thereto since the hydrocarboxy products of thenew oxidation process have other uses. They can, for example, beemployed as catalysts for chemical reactions and as intermediates in thesynthesis of other compounds. They can, for instance, be used to reducecarbonyl compounds such as ketones and aldehydes, to alcohols. They arealso useful additives for lubricating oil. It will be understood,therefore, that the invention is not limited to the examples which havebeen given by way of illustration only, nor is the invention limited byany theory proposed in explanation of the improved results which areachieved.

We claim as our invention:

1. In a process for oxidizing a compound of the formula MR where M isaluminum or boron and the Rs represent hydrocarbyl or hydrocarbyloxy(-OR) radicals of not more than 30 carbon atoms with the proviso that atleast one R is always hydrocarbyl, to produce the corresponding compoundin which each of said hydrocarbyl radicals attached to the metal atom Mis converted to a hydroca-rbyloxy radical (OR), the improvement ofeffecting the oxidation in the presence of from about 1 to about 12molar percent based on the amount of MR present of a compound of theformula R' X-*(OR') where R represents hydrocarbyl of not more than 30carbon atoms, X represents cadmium or zinc, and a and I) each representintegers from 0 to 2 such that the sum of a and b is always 2.

2. The process in accordance with claim 1 wherein X is cadmium, a is 0,b is 2, and R represents alkyl of from 2 to 20 carbon atoms.

3. The process in accordance with claim 1 wherein X is zinc, a is 0, bis 2, and R represents alkyl of from 2 to 20 carbon atoms.

4. The process in accordance with claim 3 wherein Zn(OR') is formed inthe oxidation.

5. The process in accordance with claim 1 wherein MR in which M isaluminum and R is alkyl, is oxidized with molecular oxygen to M(OR) inthe presence of Zn(OR') 6. The process in accordance with claim 5wherein R is al-kyl of 4 to 30 carbon atoms and R is alkyl.

7. The process in accordance with claim 6 wherein Zn(OR') is formed inthe mixture by oxidizing Zn(R) 8. The process in accordance with claim 7wherein the oxidation is conducted at a temperature of from about 40 toabout C.

9. The process in accordance with claim 1 wherein M is boron, R isalkyl, X is zinc, a is 2, b is O, and R is alkyl.

References Cited UNITED STATES PATENTS 12/1962 Ramsden 260-429] 12/1962Flanagan 260 448 OTHER REFERENCES Coates, G. E.: OrganometallicChemistry, second edition 1960, p. 67.

Eaborn, C.: Organosilicon Compounds, 123124.

TOBIAS E. LEVOW, Primary Examiner.

H. M. S. SNEED, Assistant Examiner.

1. IN A PROCESS FOR OXIDIZING A COMPOUND OF THE FORMULA MR3 WHERE M ISALUMINUM OR BORON AND THE R''S REPRESENT HYDROCARBYL OR HYDROCARBYLOXY(-OR) RADICALS OF NOT MORE THAN 30 CARBON ATOMS WITH THE PROVISO THAT ATLEAST ONE R IS ALWAYS HYDROCARBYL, TO PRODUCE THE CORRESPONDING COMPOUNDIN WHICH EACH OF SAID HYDROCARBYL RADICALS ATTACHED TO THE METAL ATOM MIS CONVERTED TO A HYDROCARBYLOXY RADICAL (-OR), THE IMPROVEMENT OFEFFECTING THE OXIDATION IN THE PRESENCE OF FROM ABOUT 1 TO ABOUT 12MOLAR PERCENT BASED ON THE AMOUNT OF MR3 PRESENT OF A COMPOUND OF THEFORMULA R''A-X-(OR'')B WHERE R'' REPRESENTS HYDROCARBYL OF NOT MORE THAN30 CARBON ATOMS, X REPRESENTS CADMIUM OR ZINC, AND A AND B EACHREPRESENT INTEGERS FROM 0 TO 2 SUCH THAT THE SUM OF A AND B IS ALWAYS 2.